(svn r12866) [0.6] -Backport from trunk r12759, r12717, r12682, r12564, r12561:

- Fix: Slope checking for NewGRFs failed (r12759)
- Fix: Check the TILE_NOT_SLOPED flag of the _north_ tile of multi-tile houses to decide if autoslope is allowed (r12717)
- Fix: Removing road pieces from a town gave you twice the intended penalty [FS#1920] (r12682)
- Fix: Towns could not terraform when inflation rised terraform prices enough (r12564)
- Fix: Do not affect town rating change by the order in which we examine stations (r12561)

src/newgrf_industrytiles.cpp

@@ -275,7 +275,7 @@ bool PerformIndustryTileSlopeCheck(TileIndex ind_base_tile, TileIndex ind_tile,
 		return !IsSlopeRefused(GetTileSlope(ind_tile, NULL), its->slopes_refused);
 	}
 	if (its->grf_prop.grffile->grf_version < 7) {
-		return (callback_res & 0xFF) != 0; // mask to 8 bit callback result
+		return callback_res != 0;
 	}
 
 	/* Copy some parameters from the registers to the error message text ref. stack */

src/newgrf_spritegroup.cpp

@@ -97,7 +97,7 @@ static inline bool Is8BitCallback(const ResolverObject *object)
 		case CBID_INDTILE_ACCEPT_CARGO:
 		case CBID_VEHICLE_COLOUR_MAPPING:
 		case CBID_HOUSE_PRODUCE_CARGO:
-		case CBID_INDTILE_SHAPE_CHECK: // depends on grf version, masked to 8 bit in PerformIndustryTileSlopeCheck() if needed
+		case CBID_INDTILE_SHAPE_CHECK:
 		case CBID_VEHICLE_SOUND_EFFECT:
 		case CBID_VEHICLE_MODIFY_PROPERTY: // depends on queried property
 		case CBID_CARGO_PROFIT_CALC:

src/road_cmd.cpp

@@ -103,7 +103,7 @@ static bool CheckAllowRemoveRoad(TileIndex tile, RoadBits remove, bool *edge_roa
  * @param rt roadtype to remove
  * @param crossing_check should we check if there is a tram track when we are removing road from crossing?
  */
-static CommandCost RemoveRoad(TileIndex tile, uint32 flags, RoadBits pieces, RoadType rt, bool crossing_check)
+static CommandCost RemoveRoad(TileIndex tile, uint32 flags, RoadBits pieces, RoadType rt, bool crossing_check, bool town_check = true)
 {
 	/* cost for removing inner/edge -roads */
 	static const uint16 road_remove_cost[2] = {50, 18};
@@ -141,7 +141,7 @@ static CommandCost RemoveRoad(TileIndex tile, uint32 flags, RoadBits pieces, Roa
 
 	/* check if you're allowed to remove the street owned by a town
 	 * removal allowance depends on difficulty setting */
-	if (!CheckforTownRating(flags, t, ROAD_REMOVE)) return CMD_ERROR;
+	if (town_check && !CheckforTownRating(flags, t, ROAD_REMOVE)) return CMD_ERROR;
 
 	if (!IsTileType(tile, MP_ROAD)) {
 		/* If it's the last roadtype, just clear the whole tile */
@@ -192,7 +192,7 @@ static CommandCost RemoveRoad(TileIndex tile, uint32 flags, RoadBits pieces, Roa
 			c &= present;
 			if (c == ROAD_NONE) return CMD_ERROR;
 
-			ChangeTownRating(t, -road_remove_cost[(byte)edge_road], RATING_ROAD_MINIMUM);
+			if (town_check) ChangeTownRating(t, -road_remove_cost[(byte)edge_road], RATING_ROAD_MINIMUM);
 			if (flags & DC_EXEC) {
 				present ^= c;
 				if (present == ROAD_NONE) {
@@ -227,7 +227,7 @@ static CommandCost RemoveRoad(TileIndex tile, uint32 flags, RoadBits pieces, Roa
 			if (rt == ROADTYPE_ROAD && HasTileRoadType(tile, ROADTYPE_TRAM) && (flags & DC_EXEC || crossing_check)) return CMD_ERROR;
 
 			if (rt == ROADTYPE_ROAD) {
-				ChangeTownRating(t, -road_remove_cost[(byte)edge_road], RATING_ROAD_MINIMUM);
+				if (town_check) ChangeTownRating(t, -road_remove_cost[(byte)edge_road], RATING_ROAD_MINIMUM);
 			}
 
 			if (flags & DC_EXEC) {
@@ -756,7 +756,7 @@ CommandCost CmdRemoveLongRoad(TileIndex end_tile, uint32 flags, uint32 p1, uint3
 						_additional_cash_required = DoCommand(end_tile, start_tile, p2, flags & ~DC_EXEC, CMD_REMOVE_LONG_ROAD).GetCost();
 						return cost;
 					}
-					RemoveRoad(tile, flags, bits, rt, true);
+					RemoveRoad(tile, flags, bits, rt, true, false);
 				}
 				cost.AddCost(ret);
 			}

src/town_cmd.cpp

@@ -767,7 +767,7 @@ static bool TerraformTownTile(TileIndex tile, int edges, int dir)
 	TILE_ASSERT(tile);
 
 	r = DoCommand(tile, edges, dir, DC_AUTO | DC_NO_WATER, CMD_TERRAFORM_LAND);
-	if (CmdFailed(r) || r.GetCost() >= 126 * 16) return false;
+	if (CmdFailed(r) || r.GetCost() >= (_price.terraform + 2) * 8) return false;
 	DoCommand(tile, edges, dir, DC_AUTO | DC_NO_WATER | DC_EXEC, CMD_TERRAFORM_LAND);
 	return true;
 }
@@ -1975,6 +1975,33 @@ static void DoClearTownHouseHelper(TileIndex tile)
 	DeleteAnimatedTile(tile);
 }
 
+/**
+ * Determines if a given HouseID is part of a multitile house.
+ * The given ID is set to the ID of the north tile and the TileDiff to the north tile is returned.
+ *
+ * @param house Is changed to the HouseID of the north tile of the same house
+ * @return TileDiff from the tile of the given HouseID to the north tile
+ */
+static TileIndex GetHouseNorthPart(HouseID &house)
+{
+	if (house >= 3) { // house id 0,1,2 MUST be single tile houses, or this code breaks.
+		if (GetHouseSpecs(house - 1)->building_flags & TILE_SIZE_2x1) {
+			house--;
+			return TileDiffXY(-1, 0);
+		} else if (GetHouseSpecs(house - 1)->building_flags & BUILDING_2_TILES_Y) {
+			house--;
+			return TileDiffXY(0, -1);
+		} else if (GetHouseSpecs(house - 2)->building_flags & BUILDING_HAS_4_TILES) {
+			house -= 2;
+			return TileDiffXY(-1, 0);
+		} else if (GetHouseSpecs(house - 3)->building_flags & BUILDING_HAS_4_TILES) {
+			house -= 3;
+			return TileDiffXY(-1, -1);
+		}
+	}
+	return 0;
+}
+
 void ClearTownHouse(Town *t, TileIndex tile)
 {
 	HouseID house = GetHouseType(tile);
@@ -1984,21 +2011,7 @@ void ClearTownHouse(Town *t, TileIndex tile)
 	assert(IsTileType(tile, MP_HOUSE));
 
 	/* need to align the tile to point to the upper left corner of the house */
-	if (house >= 3) { // house id 0,1,2 MUST be single tile houses, or this code breaks.
+	tile += GetHouseNorthPart(house); // modifies house to the ID of the north tile
-		if (GetHouseSpecs(house-1)->building_flags & TILE_SIZE_2x1) {
-			house--;
-			tile += TileDiffXY(-1, 0);
-		} else if (GetHouseSpecs(house-1)->building_flags & BUILDING_2_TILES_Y) {
-			house--;
-			tile += TileDiffXY(0, -1);
-		} else if (GetHouseSpecs(house-2)->building_flags & BUILDING_HAS_4_TILES) {
-			house-=2;
-			tile += TileDiffXY(-1, 0);
-		} else if (GetHouseSpecs(house-3)->building_flags & BUILDING_HAS_4_TILES) {
-			house-=3;
-			tile += TileDiffXY(-1, -1);
-		}
-	}
 
 	hs = GetHouseSpecs(house);
 
@@ -2284,15 +2297,24 @@ static void UpdateTownGrowRate(Town *t)
 		if (DistanceSquare(st->xy, t->xy) <= t->radius[0]) {
 			if (st->time_since_load <= 20 || st->time_since_unload <= 20) {
 				n++;
-				if (IsValidPlayer(st->owner) && t->ratings[st->owner] <= 1000-12)
+				if (IsValidPlayer(st->owner)) {
-					t->ratings[st->owner] += 12;
+					int new_rating = t->ratings[st->owner] + 12;
+					t->ratings[st->owner] = min(new_rating, INT16_MAX); // do not let it overflow
+				}
 			} else {
-				if (IsValidPlayer(st->owner) && t->ratings[st->owner] >= -1000+15)
+				if (IsValidPlayer(st->owner)) {
-					t->ratings[st->owner] -= 15;
+					int new_rating = t->ratings[st->owner] - 15;
+					t->ratings[st->owner] = max(new_rating, INT16_MIN);
+				}
 			}
 		}
 	}
 
+	/* clamp all ratings to valid values */
+	for (uint i = 0; i < MAX_PLAYERS; i++) {
+		t->ratings[i] = Clamp(t->ratings[i], -1000, 1000);
+	}
+
 	ClrBit(t->flags12, TOWN_IS_FUNDED);
 	if (_patches.town_growth_rate == 0 && t->fund_buildings_months == 0) return;
 
@@ -2536,7 +2558,8 @@ static CommandCost TerraformTile_Town(TileIndex tile, uint32 flags, uint z_new,
 {
 	if (AutoslopeEnabled()) {
 		HouseID house = GetHouseType(tile);
-		HouseSpec *hs = GetHouseSpecs(house);
+		GetHouseNorthPart(house); // modifies house to the ID of the north tile
+		const HouseSpec *hs = GetHouseSpecs(house);
 
 		/* Here we differ from TTDP by checking TILE_NOT_SLOPED */
 		if (((hs->building_flags & TILE_NOT_SLOPED) == 0) && !IsSteepSlope(tileh_new) &&